According to CIC website, the followings are exepmt from travel restrictions:
https://www.canada.ca/en/immigration-refugees-citizenship/services/coronavirus-covid19/immigration-applicants.html
If we already approved your permanent resident application
If you’re outside Canada
Note: If your confirmation of permanent residence (CoPR) is expired,
follow these steps.
You won’t be allowed to enter Canada right now if you’re coming to validate your CoPR and become a permanent resident,
unless you are exempt from the
travel restrictions.
You are
exempt from the current travel restrictions and can come to Canada
if you have a valid COPR and:
- the COPR was issued on or before March 18, 2020 or
- the COPR was issued after March 18th, 2020 and you are an immediate family member sponsored by a Canadian citizen or permanent resident (note that grandparents are not considered immediate family members and cannot come to Canada at this time) or
- you’re currently living in the U.S. and will be coming to Canada directly (transiting through the U.S. to Canada doesn’t apply
So,
parents(not grandparents) who got their COPRs issued under PGP program are exempt from travel resitrictions.